The present invention relates to improvements in the fixture for mounting and removing special gears, particularly in an apparatus for mounting sprocket wheels on and removing them from the free-wheel units of bicycles, described in the U.S. Pat. No. 4,157,608 of the same Applicant.
Said patent relates to an apparatus of the aforementioned type, comprising a first tool in the form of an appropriately shaped elongated metal plate, having a smooth handgrip and a functional part provided with a plurality of recesses which are shaped to receive and mate with elements of a free-wheel unit so as to prevent their rotation, each of said recesses being provided at the centre with a screw-threaded hole, said first tool comprising at least two locking pin members apt to be screwed into said screw-threaded holes and to lock in said recesses of the plate the elements of the free-wheel unit having to be handled, and a second tool in the form of a handle provided at one end with a half-moon shaped body having a length of bicycle transmission chain pivotally connected to one end thereof, said half-moon shaped body having a groove extending along the entire length of its inner circumferential edge for housing the toothed periphery of a sprocket wheel engaged by said second tool.
On using the apparatus according to said patent it has been found that the two tools forming the same could be appropriately improved to obtain a more rational, efficient and prompt use of said apparatus, and the present invention relates to such improvements the importance of which will appear particularly evident to experts when using the apparatus during cycling races.